This invention relates to equipment for extracting dust (which expression is herein intended to include fibres and lint) from looms, particularly but not exclusively those provided with Jacquard, Dobby or Cam shedding control means.
Large amounts of dust are produced during the weaving of fabrics, especially denim. If this dust is not extracted regularly it clogs the machinery, being particularly detrimental to harness cords and to the very large number of rapidly operating undermotion springs beneath a Jacquard loom. The dust also tends to contaminate the cloth, and to cause unhealthy air pollution in the weaving room. An in-depth study of the primary weaving functions shows that the majority of the dust is generated by the constant rubbing together of the warp threads during the shedding function, which may account for 70 percent of the dust, and by the rapid oscillation of the beater during the beat-up function. Significant dust is also generated by warp stop detection, and by weft insertion.
Dust extraction has usually been effected hitherto by so-called atmospheric cleaning systems entailing blowing accumulated dust from the looms and promptly collecting it by suction. Current atmospheric systems typically comprise an overhead endless track carried by the gantries conventionally disposed above rows of looms, and a unit suspended below and travelling progressively along the track and provided with at least one nozzle for blowing air to disturb the dust and with at least one duct for simultaneously sucking in the dust-laden air and delivering it to a filter cabinet. Because the unit has to travel it is relatively complex and so tends to be unreliable, and it does not extract dust continuously from every loom. Furthermore, the atmospheric system fails to collect some of the dust disturbed by its blowing action. It has also been proposed, in European Patent Specification No. 0 408 376 B, to provide loom cleaning apparatus comprising a transverse duct located below the warp sheet and containing at least one fan generating downward air flow through its permeable upper and lower walls. The duct is inside an endless filter belt having an upper dust collection run traversing the duct upper wall. A collector removes dust from the filter belt upper run, preferably by suction nozzles or a scraper. Alternatively a filter fixed across the duct top is cleaned by a moving scraper. This mechanism requires power-driven travelling parts which make it difficult to incorporate within a loom, and it only collects dust from one zone thereof.